Photoelectric marksmanship device



July 25, 1950 D. E. HOOKER PHoToELEcTRIc MARKSMANSHIP DEVICE 2 Sheets-Sheet l Filed Feb. l2, 1941 mmj July 25, 1950 D. E. HOOKER PHoToELEcTRIc MARKSMANSHIP DEVICE 2 Sheets-Sheet 2 Filed Feb. 12, 1941 Taf E BIV.

Patented .uly 25, 179450 PHoToELEoTRIc MARKsMANsHIP DEVICE Donald E. Hooker, Chicago, Ill., assignor to Raymond T. Moloney, Chicago, Ill.

Application February 12, 1941, Serial No. 378,645

This invention relates broadly to photo-electric aiming devices, and has as its principal object the provision of mechanism for projecting a moving image on a wall or screen, and anaiming device or gun adapted to be aimed at the image and including photo-electric means and associated parts actuated when the aim is ycorrect for indicating this fact to the marksman or an instructor.

A further object is the provisionof a simulated gun or other aiming device having associated therewith a photo-electric means adapted to be actuated by light reected from a target element upon which the gun is properly trained, together with means for projecting a luminous background image on a wall or screen and projecting a luminous target upon said screen and the background thereon, said target image being movable relative to the background if desired, and the background being intended to provide a suitable environmental setting for the target. For example, the background image may represent a wooded scene, and the target image may represent a moving tank or yother object of warfare.

A further and important object is the provision for means for rendering the photo-electric device sensitive to the light reflected from the target image but not that reflected from the background image or images. y

A further important object is the provision of means for controlling the movement of the target image by an instructor for purposes of training a student marksman in the manipulation of the gun or other weapon associated with the photoelectric means.

Yet another object is the provision in a marksmanship or aiming device of the class hereinabove described, of a photo-electric means which may be associated with an actual, as distinguished from simulated, weapon for the purposes aforesaid.

Still another object is the provision of photoelectric means to be associated with an actual or simulated marksmanship device or weapon, means for projecting by light an image on a target screen or wall surface adjacent the weapon, and means in the nature of a reflecting device adapted to be moved by an instructor to eiect various movements and placements of the target image on the screen or wall surface to instruct the student in the art of training the weapon upon said target image, together with means for rapidly varying the intensity of the light forming the target image for the purpose of actuating the photo-electric means.

18 claims. (ol. 27s-101.2)

Further objects reside in the provision of circuit connections and apparatus for indicating scores and for controlling the operation of the device, as well as the provision of both mobile and stationary gun units for use therewith. 1

Additional objects, advantages and novel aspects of the invention reside in the means for providing a movable target image with modulated, light with or without a luminous scenic back ground, and in certain details of construction asy well as in the cooperative relationship of the component parts of the illustrative embodiment de scribed hereinafter in view of the annexed drawings in which:

Fig. l is a schematic showing of circuit connections and the mechanical parts of one form of the invention;

Fig. 2 is a vertical section through a stationary type of gun unit with the gun shown in elevation; Fig. 3 is a schematic showing of circuit connec-y tions and mechanical parts of a modied form of` the invention;

Fig. 4 is a side elevation partly in sectiony of a,y

mobile gun unit; v

Eig. 5 is a schematic detailof the cam drive for the image defining means. Fig 6 is a longitudinal section photo-electric telescope.

through the Heretcfore, in the art pertaining to photo-` electric marksmanship devices, it has been cus.-

tomary to employ a target having some form of photosensitive means associated therewith, and a gun provided with light projecting means which was adapted to be aimed upon the photosensitive means of the target with the object of actuating.

some hit indicating or shot register means actuated by the photosensitive means. In this art also various forms of moving target and photo-electric. means associated therewith have been employed,y but such arrangements are subject to limitations'v of several kinds, both structural and functional..

In the rst place, whereas a relatively large target may be provided, the photo-electric means is necessarily restricted in size and area of sensitivity in relation to the size of the target element withv which it is associated, with the result that the marksman cannot aim at any portion of the target but must concentrate his re on a relativelyV is limited to the range of movement of the mechanical means employed to mount and move the target structure. Further, electrical connections and instrumentalities necessary in this type of structure become complicated and troublesome as the flexibility or range of movements of the target structure itself is extended.

The present invention overcomes these dimculties and greatly increases the 'flexibility 'of the target portions of such a photo-electric marksmanship device. This is accomplished in part by associating the photo-electric means with the gun or other aiming device, and providing `a luminous light-projected target and means for effecting movement of the sameovera lrelatively unlimited area.

The invention further makes'it possible to provide any desired or appropriate scenic background for the luminous target without'aifecting the photosensitive means associated with the students weapon.

yThe inventionfurther makes it possible foran instructor to control themovements of the targetrimage simply and with instantaneous Yprecision.

The-'limitations and problemspeculiar to .prior art devices are overcome, 4and the hereinabove specified robjects andvadvantages are achieved, bythe arrangement Ashown schematically inlFig. l wherein there-.is showna simulated machine gun 40 having arranged in the barrel portion thereof!a-photo-electriccell Il disposed in alignmentlwith-the muzzle portion l2. The weapon is provided with a trigger I3 arrangedtoclose .the switch i4 vwhen depressed.

flhe-gun-in is adaptedto be trained uponvarious portions of a suitable reflecting surface of a Screener wall surface l5, the extent ofwhich may beoonsiderably larger than that shown in @the drawing inactual practice,y as will appear hereinafter.

A suitable image, for example thatfof'an'fairplane Hijs projected upon the surface l5 by an arrangement including a light source 1H, an image Vdeningfdevice 16a, Vand suitablefimage forming means such asthelens l9'- by means-of which-the image defined bythe member i6a is focused upon a dirigible reflectingdeviceor mirror 2U arranged'in optical relation to the surface I5'so that the airplane image i6 maybe caused to move lon surface l5 by manipulation of the' mirror- 2 0.

v`When the mark'sman aims the gun il)v properly upon'r the target image I6, the photo-electric device' Il isv actuated, which in turn operates the amplier 22 connected therewithv by conductors 2|. Amplier=22 in turn `causes operation 'of the ampli'er Arelay23v to close switch 24 thereof thus connecting the driving pawl solenoidv25- of the hit counter unit via'conductors'26 and v2l with one terminal-of a power source or battery 28. The remaining terminal of battery or power ysource 28 is'connected incommon to contacts 29 on an interrupter switch having a rotary contact 30 driven bya motori. The rotary contactl 30 is Aconnectedby conductor 32 with one terminal'of trigger switch I4, the remaining terminal of which is `connected to ground.

Thus when trigger i3 is depressed the contacts'of switchA I4 are closed to complete a circuit through the interrupter switch contacts v29 to energize the hit counter solenoid 25 intermittently at a ratecorrespon'ding to the speedof movementiof the 'interruptor switchfwipertll Jover contacts 29. `rThis rate may bej rather-rapid-to' ratchet mechanism 33 to move a score indicating dial 3 4.

Means for controlling the operation of the envtire mechanism, includes the provision of a relea-se solenoid 3l, the remaining terminal of which is connected to battery for completion of itsoperating-,circuit to ground. Thus closure of reset svizitchsand,particularly contacts 35a and 35h xthereof :will eiect .the release .of the ,pawl and @ratchet l.mechanism.33.and permit the dial lidtozbe returnedto the normal or zero position by --the.customary:. spring means 34a.

.Glosureofswitch :35 also completes a circuit via contacts .'35a and.35e .to .conductor 38 and thence to one. sideof a. locking. relay winding 39, the remainingterminal .of which isconnected in a-power circuit Ito grounded battery. .It is intended rthatsreset switch 35-will beonly momentarilyI operated; however, .asfsoon Y as the locking relayi391-is energized Ibyclosure of switchcontacts 35u=and35c, itkmakes its own locking circuit to ground via/'contacts 39o-so that there is a holding ground Yconnection established Vto conductor -3B aslongfas the relay-39 holdsup. The aforesaid locking circuit through Acontacts :39a may be broken by openingi a zmaster vswitchn 4B.

Another result of theclosure of -reset switch y35 is *to setup `alocking circuit'- for the interrupter motor'relay-WI, asis apparent from an inspection of the diagram, resulting in a closure of `the switch^-42 thereof-which connects power to motor Biandecauses lwiper 3Uto traverse the-series of contactsfZS Vin'rapid-succession, preferably at a rateto give about'ointerruptions per minute, equivalent to 850 shots per minute.

"A A`very "important feature of `the invention residesin themeans for vrendering the photoelectric device lsensitive only to the light reflected fromithetarget `image 16, as :distinguished from the'light' in vtllesurrounding room aswell as that reflected from the background image on the screen' or other surfaceY l5.

lf the"background image or surface l5, upon which vthe `image i6 is projected, contrasts in intensity with fthelight of the target image andzl-or-ireflected fromrsaid surface, then movement of the image i5 across the optical-range of t-he-gunfii3,4 while 4the latter is held stationary, would under-ordinary Icircumstances cause an operation of the photo-electric device H and associatedampliflerZZ; owing to thel fact that the photosensitivedevice H reacts to relatively slight variations-in light intensity. Therefore, 'in .accordance vwith the usual arrangement of-suoh photo-electric devices,-it would be impossible to employa-'movingltarget image under circumstances where light could be received from the image itself eas well v)as vfrom the surrounding 'objects 'ori the background 'or screen upon :.Which the image isfprojected.

Moreover, even if the imagetwereheld-sta- 52EA tionary relative to the background, screen,for other surface I5, mere movement of the gun I in adjusting the aim would be quite likely to result in activation of the photocell II andcause false operation of the amplifier relay 23, since movement of the gun .would `cause fluctuations in the intensity of light received from the target and screen the same manner-as when the image is moved relative to the screen or back ground.

To achieve a selectivev differentiation between the light reflected from the target image and that from any surrounding surface including the background upon which the image may be'profjected, the amplier 22 is made to respond effectively only to variations of relatively rapid frequency occuring in the photosensitive device II; that is to say, the light which strikes the photosensitive device I I must varywith relatively great rapidity in order to cause the amplifier 22 to respond with sufficient output to roperate, the

relay23. This means that the light from the target image IB must vary rapidly at the critical frequency for which the amplierfz may be set or tuned or filtered.

In order to distinguish the light from the target image from other light in the manner aforesaid, the image-projecting light from source II is modulated at the frequency to which the amplifier 22 is peaked or tuned to respond effectively; for example if the input frequency is 1080 cycles per second, the light from source II must be modulated or varied at a similar frequency. It is understood thatamplier -22 may be` resonantly or discriminatively peaked to the critical frequency aforesaid or may be provided with a filter circuit to p-ass only the critical frequency and render energy at other frequencies relatively ineffectual.`

Modulation of the proj ectinglight from source II is eiected by means such as the interrupter disc k?, which is rotated by motor means contained in a housing 5I upon ,which the light source I"I is also shown mounted for. convenience. The motor (not shown) in housing 5I for rotating disc Sil is energized via a conductor 52 through contacts 39h on the holding relay 39 when the latter is locked upon being energized. The disc 50 is provided with a plurality of apertures 53 arranged circumferentially in the path of light projected from source Il toward lens I9, the apertures 53 beingsituated in correct optical relation to the .focal length of lens I9 with respect to the image forming means 16d. Obviously the frequency of interruption of the light projected by the aforesaid system, is a function of the number of holes on disc 59 as well as the speed of rotation of said disc, it being, understood that these vari-v ables are determined in each case to give the desired frequency,` in the presentY .instance 1080 cycles per second.

. From the foregoing, it willbe apparent that light varying. at the relatively low vfrequencies ordinarily encountered ,in everyday activity, will not include a frequency component of 1080 cycles of sufficient duration or intensity to cause the amplifier 22 to operate the relay 23. Thus` assuming light from sources other than the -imageprojecting means were to be interrupted by ordin ary causes such as persons moving in a room, vibration of reiiecting surfaces, and so onthe photosensitive apparatus, meaning particularly the tuned amplifier 22 thereof, would not respond effectively to operate relayv 23; even` the` light yariations. resulting from. movements 4ofpthe image I6 relative toiany background includingY the screen or surface I5, will not provide ya sufficient frequency component at 108,0 .cycles-.to cause an operation of the relay 23. .Thus it may be said that the photosensitive means is selec.- tively tuned to the image or target frequency,` and as a practical matter will respond to no other frequency which might arise from any environmental cause or source. I

In Fig. 2 it is contemplated that the gun and projecting means may be conveniently arranged as a stationary -unit in a cabinet 55 along -With a background image-projecting means such as a known type of moving picture projector 56 adapted to project a relatively large background or environmental scene upon a distant screen with the target image projected for variable movement by movable forming or defining means Ia moved by cam means 5l (see detail Fig. 5).

The arrangement of Fig. 3k is intended pri.- marily for use as an auxiliary training `device in connection with actual combat equipment, such for example as the twin machine guns 6 0, in a gunners turret of a combat plane or training turret. In such an arrangement the photoelectric cell IIa cannot be mounted in the gun but is included in an auxiliary telescope device 6I adapted to be mounted conveniently either between the twin machine guns 60 or alongside a single gun unit 60a as shown at Sla in Fig. 4=.

As seen in Fig. 6, the telescope 6I has the photocell I la mounted at one end thereof behind an aperture plate 52 which is in optical align-1 ment with a collecting lens 63 at thelopposite end of thetelescope.v A preamplifier unitSII, later to be described, is situated in the .bottom of the tube out of the path of light rays directed at the aperture in the aperture plate. The telescope tube is intended to be mounted with its long axis parallel to the axis of re of the machine guns 8B or 50a. As in the arrangement ofrFig". ,1Q there is employed a means for projecting `a target image with modulated or interrupted light, said means including for example a light source and image defining means in a housing Simand an interrupter disc 50a, similar to the parts.. 1 1-, Ia and 50 of Fig. l. The image is projected upon a mirror 20a for direction upon the screen or surface I5a.

The modified arrangement of Fig. 3 is espe-, cially suitable for use with a mobile training turret, such as indicated at 'IB in Fig. 4, and the photo-electric telescope is intended to be connected with the relatively stationary amplifier and score counting mechanism by means of a cable 1I of sufcient'length to permit movement of the turret at will in a hanger or training quarters. i

Because the signal impulses from the photoelectric cell IIa are of very weak character., and must be passed through a shielded conducting means in the cable, and because the impedance of the photo-electric device is quite high, it is found vdesirable to interpose a matching imped= ance in the line between the gun turretr and the amplifier unit with the object of lowering the impedance of the connections in the relativelyv long cable 1I. For this reason the preamplierd shown in Figs. 3 and 6 is located as close as possible to the photo-electric cell IIa, this amplifier preferably being of the resistance coupled type so that its input impedance Will closely Aapproximate the impedance of the photo-electric cell Ila, while its output impedance will be consider?- ably below that of the photo-electric cell -wh'en coupled tothe main amplifier 22a as by conductors lla.

`The output of the main amplifier 22a is con-1 nected via conductors I3 to the grid circuit 'Ma of' a. Thyratron type tube vlll, and the plate 'I5 of this tube is connected to one terminal of a hit counter 'I6 including an operating coil or solenoid like the solenoid 25 of Fig. 1 (not shown), the remaining terminal of the hit counter unit being connected via conductor 'il to one brush of an interruptor "I8 and thence via conductor 19 from the other interrupter brush and through switch 19a to one oi the power line conductors 80, the other power conductor 85 being connected by conductor BI to the cathode 82 of the Thyratron tube. i

A shot counter 83, similar to the hit counter indicated at 34 in Fig. i, and including an operating solenoid (not shown) like the solenoid 25, is connected to the power supply conductors Il and 8l for the Thyratron tube circuit so as to be operated each time the power circuit is interrupted by the interruptor lll, provided the fire control switch is on, as will be explained hereafter.

The hit counter 'i5 will be energized through the plate circuit of the Thyratron only if the photo-electric telescope device lla is properly aimed at the luminous target image on screen I5a, while theshot counter 83 will continue to register as long as the Iire control switch is on regardless of whether hits are scored or not. This is one of the novel features of the scoring means.

Conductor 8l is connected to the power line 85 via contact 86a of a nre-control relay 85 associated with the gun unit in Fig. 3, and this relay in turn is controlled by a lire-control switch 8T situated on the dash panel 88 in the gun tur ret. Closing of fire-control switch 81 energizes relay 86 closing the circuit through contacts ta to connect the lead 8l to the power lead 85 so that one side of the shot counter S3 is connected to power, the return circuit for the shot counter being effected through the interruptor lll to the power lead B0. Therefore as long as the irecontrol switch B'I vremains closed, the shot counter 83 will be rapidly energized ata rate determined by the interruptor 18. This rate is preferably xed at 850 interruptions per minute to' corre; spond approximately to actual firing practice.

So far as the operation of the modulated light means is concerned, the arrangement of Fig. 3 operates substantially in the same manner as the arrangement of Fig. 1.

Operation The device of Fig. 1 operates in the following manner:

Assuming the device to be at rest, the .reset switch 35 is closed thus momentarily grounding conductors 3E and 38 which causes ratchet release coil 3l to be energized so that the hit .counter dial 34 may return `to zero; at the .same time locking relay 39 and relay 4I pull up and hold owing Yto the locking circuit established through contacts 38a. Relay 4I and its switch 42 start the motor 3l of the interruptor switch while contacts 39h of the locking relay energize the iight projecting means vI'l-lill thus causing an image of the object-defining device itc to be projected onto the mirror 20 vand thence onto the surface I5, the light by which said images are projected being interrupted by the perforate interruptor disc 50 at a rate which `will closely approximate a resultant frequency .of 1080 cycles per second.

The student trains the gun Ill upon the image IB, which may be caused to move in various mane ners by manipulation of the mirror 20 in the hands of an instructor, and when satisfied with his aim the student depresses trigger I3 closing Switch I4 which completes the circuit through the interruptor switch means 2li-3i) thus rapidly energizing the noise-maker solenoid NS and setting up a rapid operating circuit to the Score counter or hit counter solenoid 25.

If the weapon is accurately aimed, the modulated light from image I6 will rapidly actuate the photocell II and the ampliiier will be impulsed at its tuned or peaked frequency and hence will cause the amplier relay 23 to pull up closing switch 24 so that the hit counter solenoid 25 will be energized intermittently at a rate depending upon the rate of the interrupter switch 30. This rate is preferably 850 interruptions per minute, corresponding to the ring rate of one type of machine gun.

Thus as long as the students aim is held accurately on the image IE, the hit counter will be rapidly stepped forward. Should the weapon continue to be correctly aimed but the trigger switch Ill opened or released, the photo-electric mechanism would respond but the hit counter would not register owing to the ineiiectiveness of the interruptor switch 30. Likewise, should the trigger switch continue to be depressed but the aim lost, the interrupter switch would continue to operate but no score would be stepped up on the counter 34 because relay 23 would not be pulled up by operation of the photo-electric means.

If it is desired to reset the score counter, reset switch 35 is closed causing the ratchet release solenoid 31 to withdraw the ratchet dog so that the score dial 34 may return to zero. To stop the entire mechanism, master switch 40 may be opened, thus breaking the ground circuit through contacts 39a and 39h, causing locking relays 39 and 4I to drop out.

Operation of the arrangement of Fig. 3 is as follows:

Assuming the main power switch 81X to be closed, a modulated image I6b will be projected on the screen lia from mirror 20c, by operation of the projector lamp and image deiining means (identical to means Il and Ia of Fig. 1) associated with housing Sia, the image being intere rupted at a frequency of i080 C. P. S. by a disc 50a identical with disc 50 or" Fig. l. The student inthe Vgun turret trains the guns 60 upon the image IGI), and if his aim is correct, light reiiected from the image on screen or surface I5a will be focused upon the photocell IIa, in the photo-electric telescope 6I through lens 63 and aperture 62.

When the photo-electric cell IIa is struck by light and activated as aforesaid, the small preamplifier 64 in the telescope is actuated and the electrical impulse therefrom carried through the shielded cable 'II to the input of the main amplifier 22a. The output of the amplier is passed to the grid circuit 14a of the Thyratron tube Il thus completing an energizing circuit for hit counter 1E (constructed similarly to the means 25-.7-33 of Fig. l). The latter circuit is interrupted at 850 breaks per minute by the interrupter 'it (assuming target switch 19a to be closed) and the hit counter will be rapidly ad- Vanced if the aim is correct, providing the iii-econtrol switch 8l on the dash board of the training turret is closed to complete the circuit counter 83 (similar in construction to the parts 25-33-34 of Fig. l) Will'bezadvanced. Thescore is calculated by `comparing the readings of the hit and shot counters which may be `reset by means similar to that shown in Fig. 1 and included in the block diagram of the'counters in Fig. 3.

AIt Will appear that by locating the photocell in the gun or in association with the gun or other Weapon, and by projecting a luminous target image on a suitable surface, it is possible to increase the flexibility of the target structure to the point where there is no limit .to the movement or movements which can be imparted vvto means, actual firing conditions inherent in the y present day use of high speed machine guns, it having been impossible heretofore to approach anything like 850 shots a minute with a projected light to cause operation of a photo-electric target capable of registering any substantial portion of the successful hits. By employing a luminous image for a target as distiguished from some form of physical target structure, and by using a trigger controlled interrupter circuit breaker operating at the approximate ring speed, the eiiiciency of the marksmans aim can be determined by consulting the score actually registered or indicated as a function of the number of shots registered or indicated. In this Way a very close approach to real conditions is achieved without any sacrice of accuracy, and the equipment may be used in conjunction with actual combat weapons or simulated weapons adapted to house the photo-electric means. The various advantages and objects of the invention may be realized by modifications ofthe particular devices and embodiments speciiically described herein, and it is the intention that the appended claims shall include all equivalent arrangements and constructions fairly coming within their call.

Having thus described my invention, what I claim as new and desire to protect by Letters-Patent of the United States is:

1. In photoelectric marksrnanshipv apparatus, in combination, a photosensitive device and amplifier means associated therewith, said amplifier means being tuned to give maximum response to a predetermined frequency, means folprojecting a luminous target image, said photosensitive device being adapted to be aimed at said image,` and means for modulating Vthe image-projecting light at a frequency closely approximating that to which said amplifier means is tuned,and hit-indieating means operably controlled'by said amplier means responsive to actuation of said photosensitive device when properly aimed at said image.

2. In a photoelectric marksmanship apparatus,

in combination, a source of modulated light for z5 `10 projecting a targetimage, and aiming means including a light sensitive element adapted to be aimed at said yimage for actuation by modulated light received therefrom, together with modulation-selective hit-indicating means actuated by said light sensitive element and arranged to give an indication of a hit only when said element Iis actuated bylight having substantially the same modulation characteristics as the image projecting light. 4

:3. In aphoto-electric marksmanship device, in combination, a source of `modulated light for proljecting a target image, a photosensitive aiming device adapted to '.beaimed at said image, and amplifying means operably associated with said photosensitive device and tuned to give a maximum; response at a modulation frequency corresponding to that of the modulated light from said source,-and Ahit-in'clicating means .actuated by maximum response of said amplifying means.

4. In a photoelectric marksmanship apparatus, a source of light for projecting a target image, a photoelectric aiming device adapted to be aimed at said image, hit-indicating means actuated by said photoelectric device as a result of proper aiming-of the latter upon said image, means for interrupting the projecting light from said source at a .predeterminedrata and meansy cooperating with said hit-indicating means for rendering the lattereiectively responsive to indicate a hit only when said hit-indicating means is actuated by said 4photoelectric device by impulses therefrom occurring at substantially the same rate as the Hpredetermined rate aforesaid.

. `5. In a device of the class described, in combinationmeans for` projecting light to define a target, aiming means including light-sensitive means adapted to be aimed at said target, electrical hit-indicating means operably controlled by saidlight-sensitive means, means for varying the intensity of the projected target-defining light in a predetermined manner, and means for rendering said electrical hit-indicating vmeans selectively responsive to indicate a hit only when said light-sensitive means isactuated bylight varying in the-predetermined manner aforesaid.

6. In a photcelectric marksmanship device, in combination, means for projecting light to define aluminous target, means for projecting light to define a luminous background for said target, photosensitive aiming meansadapted to be aimed at said target, selective electrical hit-indicating means operably controlled by said vphotosensitive aiming means-and means for rendering said hit-indicating means effectively responsive only to operations of said photosensitive aiming means which Iare caused by vlight from said target as distinguished from said background.

7. A photoelectric-'marksmanship ldevice 'comprising, in combination, a'photosensitive aiming means, amplifying means actuated by said photosensitive aimingmean's, hit-indicating means actuated by said amplifying means, means for projecting a luminous target on a receiving surface, means for vprojecting a luminous background on said surface for said target, meansfor modifying the light from one of the aforesaid projecting means to distinguish said light from that of the other projecting means, rand means for rendering said amplifying means selectively responsive to actuate said hit-indicating means only by actuationrof the photosensitive means by light from the target. y

l 8. In a photoelectric marksmanship apparatus, in combination, a source of light modulated as to andere l frequency in a predetermined manner for nenn: ing a target, aimable pnetosiisiuve means adapted 'to be 'directed at said target, irequeriy selective r'iieans operativ ccntr'cned by said pi insensitive means 4fory giving an indicatin only 'ivlren said photos'ensitiv 'in'eans is 'airhed at a luminous target the luminosity 'of which is moda# fated in substantially the vsaine predetermined manner aforesaid. 9, In a device of the class described, coinbinatio, means for projecting light f varying intensity to den'e a target, neans Yfor selectively directing said light to alter the 'position of the target ai win, e, pilote-sensitive aiming' device adapted i@ be aimed at said "target, ineens @een abrir @finden 'bv ma piitesensinve aiming device for indicating ivhen the aiming device 'is tfaiied'on a luminous target, and means cooperable withv said indicating 'ans for rende :n the-'saine effectively responsive to in d'ica't 'do reo't ai'n 'on 1y by controlling actions 'of said 'phot sensitive aiming inea-ns 'responsive to actuation thereof light vaiyig in intensity at "a rate corre' nding to that which defines the target as a:fore'said.

s described, in coin'- ng a linniiirlns target lien-indicating 'die iight 'from said ing means at 'a certain rate, aiming means, ir'relu ng, 'pliotosensitive 'apparatus vactuated as airesult'of directing the aiming neans alt a luln'inous target, h it indicating vmeans actuated 'by 'said pbotosensiti've appaiatus, 'means 'for l"causing said photosenstive apparatis to actuate the hit indicating 'm'ea'ns'only response to ixnpn'gemen-t on the photosler'sitive part df the aiming nieas of light 'interrupted at the afrsaid cer tain rate.

i1. pparatn`s of the blass described compriscomb'ination 'eans v'f or projecting fa means Afor "selectively prgeting a target Yiriegge dgjsaic surface with sait background inne, qnjctosensitivejainiing means iciii'd'iiig prieto- 'sensitive inefa'nsfrespons'ive 'to ligflft -fro'm'said surf ace, means for modulating the light defining 'said target vinfrage ata frequency li'vhich predomi- "Iia'ntlyfdistinet from frec'n'ienies "result-ing Afrom tion of notion pict'ie's "as aforesaid, hit- `indica-'ti'rig means lop'eradily controlled by fsaid pnotose'nsitive means, and means for preventing indication of a hit as a result f light-actuation said photosensitive means 'except by light premi'nantly of said-modulated frequency.

12. A target practice'devicecornpisinga target, a laip for illuminating 'said target, a shutter associated with said lamb adapted 'to varyjtheihtensity of light thfoit va'lffit fien't an aim'ir'igdevice, a photeletr'ic oei-1 vasscciated with Vsaid aiming device and adapted to receive light from said target, anplf'i tiid It' Ethe 'frequency of said AYshutter operatively 'connected 'to saidjphotoelectric cell, 'and indicating means operatively connected to said arnplier.

13. A 'target practice 'device comprising 'a sereni, a preiectdr Asida-puin te 'project iight eening an image 'upon 'said screen, means 'for i'n''fyig the projected light ait a 'de'lite fre'- due'ncy, an aiming device, 'photelectric means ``S`Sitd with "Sa-id 'aifflng device and 'adapted to receive light from 'said screen, 'an 'ampliiicr J'ertVly oneot'ed to'said photolectrcnns tuned to amplify imp ulses of said lirezii'ecy, ATand indicating means connected to the output of said nip'lir.

amplifier 'when receiving "suoli npiilses', a svi/itchv 'controlled by said relay, a trigger switch associ ated vvitli the rst said svvith, and hit indizatng inea-ns controlled by said switches.

155. A target practice device conipris'ing a screen, a projector 'adapted to 'project a 'iight image vvvitlji a dark background thereon, means for 'modifying the 'intensity of the projected light at a definite frequency, an aiming device adapted to be directed tovvard's the image on the screen, a photelectricceli associated vvith 'said aiming Adevice and adapted to receive light from said image when the aiming device is properly vdirected, an amplifier associated with said photoeiectr'ic cell tuned 'tosaid frequency, a relay operatively associated With said amplifier, a normally open switch adapted to .beclosed by said relay, and hit indicating means adapted to be rendered operative by said switch in closed condition.

16. Apparatus of the class described including a source of. light for projecting target images, an image-forming device mounted for movement in the path of said light to outline a target image on a light-receiving surface, an aiming device adapted to beaimed at said target image, said aiming device including photoelectric means actuated by -light received from said image, hitvindicating means actuated by said .photoelectric means, means for interrupting light from said source ata predetermined 4frequency rate greater tiran any frequency component of light fluctuation -or variation caused 11g/,movements of said image-downing device in the path of light from the source as aforesaid, and means Ainterposed operatively rbetween `said .photoelectric means and said hit-indicating means for preventing operation of 'the latter by light-actuation of the fphotoelectric -'means -atl-frequency rates other than said predetermined rate, and means `for moving 'said image-forming device.

17. In combination, a source of modulated light for casting a `lumirmus target image, 'and a vmotion picture projector for casting a backgroundv image or images for Asaid ltarget image, the modulating `frequency of said source being predetermined to provide in predominance yfre- 'du'encies oid-ight variation differing from' the -frequencies Vattending casting of the background image as aforesaid; and an 'aiming device vincluding photosensitivemeans 'and bit-'indicating means discriminatively `responsive to light variations which are predominantly of the modulating Ifrequency aforesaid.

1B. Photoelectric target apparatus including a source of 'fluctuating light of mined `rates lof uctuation 'and adaptedto bedirected upcnfa receiving member to depict a composite target yit'nalge'atfleastone portion vof which image is deried by alight from said source having a pren determined 'rate of fluctuation, and at leastone other portion "of `which vimage is dei-ined by llight from'fsaid' source 'having random lrates of iluotuae tion, an aimable photoelectric device actuated by light from said receiving imember, electrical translating 'means actuated Vby 4said photoelectri'c device and selectively responsive only to the rate of fluctuation of said light having said predetermined rate, andjndicating means actuated by said translating means in the selective operation thereof as aforesaid.

DONALD E. HOOKER.

REFERENCES CITED The following references are of record in the flle of this patent:

UNITED STATES PATENTS Number Name Date Cummings Sept. 17, 1912 Ellis Feb. 13, 1934 Foisy May 26, 1936 Kollmayer et al. Aug. 10, 1937 Sauerbier Dec. 6, 1938 Schlesinger Dec. 31, 1940 Weddington Jan. 28, 1941 Wood Mar. 25, 1941 

